Engine light on 2.5 diesel
 

My car is an 2001 grand voyager 2.5 crd with manual transmission. Whenever the accelerator pedal is pressed further than halfway the engine management light comes on and there's some loss in power. Ease off the accelerator and within 15 to 20 seconds the light goes off and normal power is resumed. Any ideas?

Just to add, my in laws used to have it serviced by a chrysler dealer, but for the last two years they have been forced to use a local independant garage who are known to be utterly useless at the best of times and did not reset the 'service required' indicator. May not be related but thought i'd mention it.

Would love to hear ideas as have a similar issue engine light on but no code that involves anything like that only p1685 which is skim which is weird as van starts fine but also when driving along throttle goes i usually pull over and restart van which seems to work but the light stays on

Just done a key dance and it brings up code p0235. A search reveals Turbocharger Boost Sensor A Circuit Malfunction. Correct?